Urasonic waves and infrasonic waves

Physics presentation on waves and its uses....

1. The word ultrasonic combines the Latin roots ultra, meaning ‘beyond’ and sonic, or sound. The sound waves having frequencies above the audible range i.e. above 20000Hz are called ultrasonic waves. Generally these waves are called as high frequency waves. The field of ultrasonics have applications for imaging, detection and navigation. The broad sectors of society that regularly apply ultrasonic technology are the medical community, industry, the military and private citizens.

2. Applications:: 1.Engineering Detection of flaws in metals (Non Destructive Testing –NDT )

3. It is the most cheap technique employed for cleaning various parts of the machine, electronic assembles , armatures, watches etc., which cannot be easily cleaned by other methods.

4. The method consists of sending a powerful beam of ultrasonics in the suspected direction in water. By noting the time interval between the emission and receipt of beam after reflection, the distance of the object can be easily calculated. The change in frequency of the echo signal due to the Dopper effect helps to determine the velocity of the body and its direction.

5. Sonar is used in the location of shipwrecks and submarines on the bottom of the sea. It is used for fish-finding application . It is used for seismic su rv ey .

6. Treating malignant tumors and other disorders, via a process known as Focused Ultrasound Surgery (FUS) or HIFU, High Intensity Focused Ultrasound. These procedures generally use lower frequencies than medical diagnostic ultrasound (from 250kHz to 2000kHz), but significantly higher time-averaged intensities.

7. Ultrasonic waves are used for studying the blood flow by measuring the change in their frequency produced due to Doppler’s effect .

8. Ultrasonic waves are used for guiding the blind who carries a walking stick containing an ultrasonic transmitter and receiver. Ultrasonic signals reflected from any obstacles are fed to the head phones through a suitable electronic circuit which enables the blind person to detect and estimate the distance of the obstacle.

9. Scientists often use in research, for instant to break up high molecular weight polymers, thus creating new plastic materials. Indeed, ultrasound also makes it possible to determine the molecular weight of liquid polymers, and to conduct other forms of investigation on the physical properties of materials. Ultrasonic can also speed up certain chemical reactions. Hence it has gained application in agriculture, that seeds subjected to ultrasound may germinate more rapidly and produce higher yields.

10. Infrasound,  sometimes referred to as low-frequency sound, is sound that is lower in frequency than 20 Hz (Hertz) or cycles per second, the "normal" limit of human hearing. Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high. The ear is the primary organ for sensing infrasound, but at higher intensities it is possible to feel infrasound vibrations in various parts of the body.

11. Infrasonic wave: the waves of frequency less than 20Hz are known as infrasonic waves. The infrasonic waves are produced by large vibrating bodies. These waves are not audible to a human ear. For example, infrasonic waves are produced by the vibration of the earth’s surface during the earthquake. Some animals like elephants, rhinoceroses and whales etc. also produce infrasonic waves. Application of infrasonic waves: there are following applications of infrasonic waves. a     Infrasonic waves are produced by large vibrating bodies. b.      Its frequency is less than 20 Hz. Infrasonics

12. Using infrasonic wave to detect and locate the leakage of pipelines, can not only detect slow leakage of pipelines with little discharge on line, but also detect high compression ratio gas pipeline leak, which overcomes some shortages of detecting methods on line such as negative pressure wave. Infrasonic wave is suitable for leakage detection of all oil gas pipelines Detection of leakages:

13. Depending on the pitch, infrasound can cause physical pressure, fear, disorientation, negative physical and mental symptoms, explode matter, incapacitate, and kill. For example, in World War II, Nazi propaganda engineers used infrasound to stir up anger in the large crowds that had gathered to hear Hitler. The result was a nation filled with anger and hatred.

14. " Acoustic Bullets . High power, very low frequency waves emitted from one to two meter antenna dishes. Results in blunt object trauma from waves generated in front of the target. Effects range from discomfort to death. A Russian device that can propel a 10-herz sonic bullet the size of a baseball hundreds of yards is thought to exist. Proposed fixed site defense. Also known as sonic bullets." (Source - Glossary of Non-lethal weapons Terms, edited by Robert Bunker) Weapon:

15. It has been known that certain whiles are able to stun their prey with powerful blasts of inaudible sounds, called 'gunshots,‘. Whales focus these powerful blasts at large squid and other fish to paralyze and catch them. In some instances, they have been known to burst their prey apart by tonal projection alone. These are found to be infrasonic waves.